Cooktop In Island No Vent . The vent must be turned on 20 minutes prior to cooking to generate enough suction to be really useful. Adding a kitchen island cooktop, like any other home improvement project, requires a lot of forethought. 36 in. Ducted Island Range Hood Cosmo Appliances (663ISS75) from www.premiumappliances.net Our top pick for the best gas cooktop with downdraft ventilation is the kitchenaid 36” kcgd506gss 5 burner cooktop! The pros of an island cooktop include a more social cooking setup, more cooking options, and creating a kitchen with a modern, unique appeal. This blue ocean island mount range hood is a quiet island vent that is a powerful yet quiet hood that has 900 cfm with noise level are 65 db.